US 7,761,125 B1 · Intermodulation distortion reduction methodology for high temperature superconductor microwave filters

Abstract

Intermodulation distortion (IMD) is known to be an impediment to progress in superconductor-based filter technology. The present invention's methodology for reducing IMD can open doors to heretofore unseen practical applications involving high temperature superconductor (HTS) filters. Typical inventive practice includes (a) increasing the thickness d, and/or (b) changing the operation temperature T, of the filter's HTS film. The film's thickness d is increased in such a way as to decrease the IMD power PIMD in accordance with the material-independent proportionate relationship PIMD∝1/d1.5-6. The film's operation temperature T is bettered or optimized in accordance with the material-independent proportionate relationship PIMD∝(λO(T))10(K(2)(T))2/(ΔO(T))6, and further in accordance with three individual material-dependent relationships, namely, between operation temperature T and each of linear penetration depth λO, gap maximum ΔO, and kernel K(2). Some inventive embodiments include oxygen overdoping of the film as an additional/alternative IMD-reductive measure.

Claims12

Dependent claims

A method for improving performance of electronic apparatus that includes superconductor film, the method comprising:

determining a first power PIMD-1, said first power p1 being the power of intermodulation distortion characterizing said electric apparatus;
determining a first thickness d1, said first thickness d1 being the thickness of said superconductor film;
selecting a second power PIMD-2, said second power PIMD-2 being a power of intermodulation distortion characterizing said electric apparatus that is less than said first power PIMD-1;
determining a second thickness d2, said second thickness d2 being a thickness of said superconductor film that is greater than said first thickness d1, said determining of said second thickness d2 including calculating said second thickness d2 in accordance with the equation
(PIMD-1)(d1)x=(PIMD-2)(d2)x,
said calculation of said second thickness d2 including selecting a value of x between 1.5 and 6;
and
increasing the thickness of said superconductor film from said first thickness d1 to said second thickness d2, thereby reducing the power of intermodulation distortion characterizing said electric apparatus from said first power PIMD-1 to at least approximately said second power PIMD-2.

5 more elements

A method for improving performance of electronic apparatus that includes superconductor film, the method comprising:

determining a first power PIMD-1, said first power PIMD-1 being the power of intermodulation distortion characterizing said electric apparatus;
determining a first operation temperature T1, said first operation temperature T1 being the unchanged operation temperature T of said superconductor film;
selecting a second power PIMD-2, said second power PIMD-2 being a power of intermodulation distortion characterizing said electric apparatus that is less than said first power PIMD-1;
determining a second operation temperature T2, said second operation temperature T2 being an operation temperature T of said superconductor film that differs from said first operation temperature T1, said determining of said second operation temperature T2 including calculating said second operation temperature T2 in accordance with the equation
(PIMD-1)(ΔO(T1))6(λO(T2))10(K(2)(T2))2=(PIMD-2)(ΔO(T2))6(λO(T1))10(K(2)(T1))2;
and;
changing the operation temperature T of said superconductor film from said first operation temperature T1 to said second operation temperature T2, thereby reducing the power of intermodulation distortion characterizing said electric apparatus from said first power PIMD-1 to at least approximately said second power PIMD-2;
wherein:
K
(
2
)
⁡
(
T
)
=
q
S
4
⁢
αμ
2
⁢
k
F
⁡
(
c
^
)
π
3
⁢
β
⁢
⁢
m
ab
⁢
c
2
⁡
(
ℏ
⁢
⁢
c
)
⁢
∑
n
=
-
∞
∞
⁢
∫
0
2
⁢
π
⁢
ⅆ
θ
⁡
(
cos
4
⁢
θ
)
⁢
(
cos
2
⁢
2
⁢
θ
)
⁢
(
cos
2
⁢
2
⁢
θ
-
(
2
⁢
ℏω
n
/
Δ
0
⁡
(
T
)
)
2
)
(
cos
2
⁢
2
⁢
θ
+
(
ℏ
⁢
⁢
ω
n
/
Δ
0
⁡
(
T
)
)
2
)
7
/
2
;
qs is the charge of a single carrier;
α≈2 is a dimensionless geometrical factor;
β=1/(kBT);
kB is the Boltzman constant;
c is the speed of light;
=h/(2π);
h is Planck's constant;
ω=((2n+1)π)/(β);
n is a positive or negative integer;
λO(T) is the linear penetration depth at operation temperature T;
ΔO(T) is the gap maximum at operation temperature T;
μ is the Fermi energy;
kF(ĉ) is the Fermi momentum in the ĉ crystal-axis direction;
mab is the effective mass in the ab crystal plane.

144 more elements

A method for improving performance of electronic apparatus that includes superconductor film, the method comprising:

determining a first power PIMD-1, said first power PIMD-1 being the power of intermodulation distortion characterizing said electric apparatus;
determining a first thickness d1, said first thickness d1 being the thickness of said superconductor film;
determining a first operation temperature T1, said first operation temperature T1 being the unchanged operation temperature T of said superconductor film;
selecting a second power PIMD-2, said second power PIMD-2 being a power of intermodulation distortion characterizing said electric apparatus that is less than said first power PIMD-1;
determining a second thickness d2, said second thickness d2 being a thickness of said superconductor film that is greater than said first thickness d1;
determining a second operation temperature T2, said second operation temperature T2 being an operation temperature T of said superconductor film that differs from said first operation temperature T1;
increasing the thickness of said superconductor film from said first thickness d1 to said second thickness d2;
and
changing the operation temperature T of said superconductor film from said first operation temperature T1 to said second operation temperature T2;
wherein said determining of said second thickness d2 and said determining of said second operation temperature T2 include finding values of said second thickness d2 and said second operation temperature T2 in accordance with the equation
(PIMD-1)(d1)x(ΔO(T1))6(λO(T2))10(K(2)(T2))2(I2)6=(PIMD-2)(d2)x(ΔO(T2))6(λO(T1))10(K(2)(T1))2(I1)6;
wherein said calculation, of said second thickness d2 and said second operation temperature T2 includes selecting a value of x between 1.5 and 6;
wherein said increasing of the thickness of said superconductor film and said changing of the operation temperature T of said superconductor film result in reduction of the power of intermodulation distortion characterizing said electric apparatus from said first power PIMD-1 to at least approximately said second power PIMD-2;
and
wherein:
K
(
2
)
⁡
(
T
)
=
q
S
4
⁢
αμ
2
⁢
k
F
⁡
(
c
^
)
π
3
⁢
β
⁢
⁢
m
ab
⁢
c
2
⁡
(
ℏ
⁢
⁢
c
)
⁢
∑
n
=
-
∞
∞
⁢
∫
0
2
⁢
π
⁢
ⅆ
θ
⁡
(
cos
4
⁢
θ
)
⁢
(
cos
2
⁢
2
⁢
θ
)
⁢
(
cos
2
⁢
2
⁢
θ
-
(
2
⁢
ℏω
n
/
Δ
0
⁡
(
T
)
)
2
)
(
cos
2
⁢
2
⁢
θ
+
(
ℏ
⁢
⁢
ω
n
/
Δ
0
⁡
(
T
)
)
2
)
7
/
2
;
qs is the charge of a single carrier;
α=2 is a dimensionless geometrical factor;
β=1/(kBT);
kB is the Holtzman constant;
c is the speed of light;
=h/(2π);
h is Planck's constant;
ωn=((2n+1)π/(β);
n is a positive or negative integer;
λO(T) is the linear penetration depth at operation temperature T;
ΔO(T) is the gap maximum at operation temperature T;
μ is the Fermi energy;
kF(ĉ) is the Fermi momentum in the ĉ crystal-axis direction;
mab is the effective mass in the ab crystal plane;
I is the total current conducted by said superconductor film.

152 more elements

Dependencies are inferred from the claim text.

Intermodulation distortion reduction methodology for high temperature superconductor microwave filters

Life of this patent

Intermodulation distortion reduction methodology for high temperature superconductor microwave filters

Life of this patent

Abstract

Claims12